Competition kinetics using the UV/H2O2 process: hydroxyl radicals reactivity with nitroaromatics

FERNANDO S. GARCÍA EINSCHLAG; LUCIANO CARLOS; ALBERTO L. CAPPARELLI

Sante Fe, Argentina

Workshop; International seminar on Advanced Oxidation Technologies; 2002

UV/H2O2 oxidation technology is frequently employed for degradation of pollutants. The efficiency of the oxidation process strongly depends on experimental conditions. We have recently shown that, the efficiency of the UV/H2O2 process for the oxidation of nitroaromatic compounds can be analyzed using a very simple mechanistic approach. In this context one of the parameters that govern the overall kinetic behavior is the rate constant for the reaction of hydroxyl radicals with the nitroaromatic compounds. An evaluation of these rate constants is possible by performing competition experiments where a given substrate competes for HO· radicals with a reference compound whose reactivity towards HO· is already known. In the present communication we analyze the reactivity of hydroxyl radicals with a series of nitroaromatic compounds using a competition kinetics scheme in the frame of the UV/H2O2 technique. Rate constant values for HO· with the substrates 1-Chloro-2,4-dinitrobenzene (CDNB), 2,4-dinitrophenol (DNP), 3-nitrophenol (MNP), 4-nitrophenol (PNP), nitrobenzene (NBE), 4-Chloro-3,5-dinitrobenzoic acid (CDNBA), 1,3-dinitrobenzene (DNB), 3-nitrotoluene (MNT) and 4-nitrotoluene (PNT) were obtained from competitive experiments.